Seroepidemiology of cholera in Gulf coastal Texas

Single serum samples from 559 volunteers from a Texas Gulf Coast area were examined for vibriocidal antibody to Vibrio cholerae O1 (biotype El Tor, serotype Inaba) by a microtiter method. Elevated levels of vibriocidal antibody were present in 14% of the subjects. Also, 6.8% of the subjects had elevated levels of antibody to the enterotoxin of V. cholerae O1 by the immunoglobulin G enzyme-linked immunosorbent assay. Recent infection, defined on the basis of elevations in both vibriocidal and antitoxin antibodies, had occurred in 1.3% of the subjects. When subjects who reported Brucella infection, travel to a cholera-endemic area, and/or cholera vaccination within a year of the study were removed from the analysis, a prevalence of recent infection of 0.89% was obtained. Significantly higher titers of vibriocidal antibody were found in those with exposure to seawater (fishermen, shrimpers, merchant marines, and dock workers) than in those without such exposure (P less than 0.005). Furthermore, titers of antitoxin antibody were significantly higher in those who consumed shellfish than in nonconsumers. Finally, titers of vibriocidal antibody were significantly higher in Vietnamese subjects than in non-Vietnamese subjects. The results of this study indicate that an endemic focus of infection with V. cholerae occurs in this area.